4 Replies Latest reply on Apr 29, 2015 12:35 PM by eos3fan

    How can my end user password-protect a document that has been digitally signed?

    eos3fan

      Hello,

       

      I have seen some threads that indirectly address parts of this question, but am still left unsure about whether this process can be done - and if it can, I could use your help in understanding it - thank you.

       

      Two of our end users use digital signatures (certificate-based) in Acrobat 9 Pro to sign documents attesting the accuracy & calibration status of lab equipment for use in a legal environment.  These end users are concerned that their documents could be altered or edited, and asked me if password protection can also be applied to their documents that need to be digitally signed.

       

      Thank you in advance for your advice.

        • 1. Re: How can my end user password-protect a document that has been digitally signed?
          IsakTen Level 4

          PDF must be encrypted before signing with a digital (certificate-based) signature. Signing hashes the bytes of a PDF file and if encryption were possible after signing, it would have changed the bytes in the file and the hash in the signature would not match the hash of the encrypted bytes, making the signature invalid.

          • 2. Re: How can my end user password-protect a document that has been digitally signed?
            eos3fan Level 1

            isakten wrote:

             

            PDF must be encrypted before signing with a digital (certificate-based) signature. Signing hashes the bytes of a PDF file and if encryption were possible after signing, it would have changed the bytes in the file and the hash in the signature would not match the hash of the encrypted bytes, making the signature invalid.

            Thank you, IsakTen - I followed that procedure, and was not successful - assuming I am doing something incorrectly.  Encrypted the document with a password (with editing fully restricted) and saved the document.  Once saved and secured with a password, am unable to place my signature - am only able to do that if I remove password security first...  What am I missing?  Thank you.

            • 3. Re: How can my end user password-protect a document that has been digitally signed?
              IsakTen Level 4

              Do you apply "Open" password or "Permissions" password or both? If you apply "Permissions" password (with or without the "Open" password) make sure that "Changes Allowed" include Filling in form fields and signing existing signature fields" or "Commenting, filling in form fields and signing existing signature fields". If permissions do not allow you to sign, you cannot sign.

              Be aware of the alert that Acrobat pops up when you apply "Permissions" password that all Adobe products respect permissions that you set but that 3rd-party PDF Viewers may not (and many do not).

              • 4. Re: How can my end user password-protect a document that has been digitally signed?
                eos3fan Level 1

                isakten wrote:

                 

                Do you apply "Open" password or "Permissions" password or both? If you apply "Permissions" password (with or without the "Open" password) make sure that "Changes Allowed" include Filling in form fields and signing existing signature fields" or "Commenting, filling in form fields and signing existing signature fields". If permissions do not allow you to sign, you cannot sign.

                Be aware of the alert that Acrobat pops up when you apply "Permissions" password that all Adobe products respect permissions that you set but that 3rd-party PDF Viewers may not (and many do not).

                That is exactly what I was missing! I apply only "Permissions" password, but had the "Changes Allowed" drop-down set incorrectly - it was set to "None."  After changing that setting to allow "Filling in form fields and signing existing signature fields," the end user was able to digitally sign the document, her desired goal.

                 

                Thank you so much.